BEI IDEACODSAS Espace Européen de l’Entreprise
9, rue de Copenhague B.P. 70044 Schiltigheim F 67013 Strasbourg Cedex Tél : +33 (0)3 88 20 80 80Fax : +33 (0)3 88 20 87 87
Mail : info@bei-ideacod.com Web : www.bei-ideacod.com DESCRIPTION
An industrial
optical encoder is an
angular position sensor: The optical diskwith dark andclear radiallines is mounted on the rotating shaft oftheencoder A source of light (light emittingdiode - LED) isused. The light fromthe LED crossesthelines on the disk and creates an analogue signalin the receptor. BEIIDEACOD
industrial encoders use the differential reading method, helping to compensate the reductionof the amplitude ofthe signals due to wearing ofthe
industrial bearings and the opticalcomponents age This signal is electronically amplified then converted intoa numeric signal which can be read by a subsequentelectronic control system(
PLC, display…)The incremental encoders simply countsthe number of pulses engraved on the disk, theycan’t memorizetheir position in case of power shut-down, it is necessary to find outthe datum point ateachnew start of cycle. Our POLYFASS® disks, mylar-mica composite,are unbreakable.The use of glass disk insures on the DIGISINE™ range a high stability level even in high resolutions.
INCREMENTALENCODERS ELECTRICAL CARACTERISTICS (AND TACHO-ENCODERS)
A, A/,B, B/, 0, 0/ output signals Channel B arrives before A in a clockwisedirection seen from the shaft side for shafted encoders or
bearing housing side for the hollow
shaft encoders.The 90°electrical phase-shift between A and B signals determines the rotation direction: Clockwise,duringthe mounting frontof A signal, B signal is 1
Industrial counter clockwise, duringthe mounting front of Asignal, B signal is 0 Period 360° electrical Gated A &t B :code 9 ‘’Top 0’’ calibration Gated A(1/2 period) :code A On a theB period :code N The maximum frequency of the incremental signals delivered by an incremental encoder is 100kHz(300kHz in DIGISINE™ version)Most PLCS/counters are equipped with quadrature inputs, whichenable themtomultiply by 2 or 4 thedisk resolution. 10 000 measure steps can be generated with A and B signals of an encoder which has a resolution of 2500 pulses per turnThe resolution of the encoders must be chosen in respect of the precision needed for your application (positioning, speed, 360pulses per revolution for a degree indication,etc). It is importantto check these points. F = N x R / 60 Example F: incremental signal frequency F = 12,8 kHz N: rotationspeed (rpm) N = 3 000 rpm R :resolution (pulses per revolution ppr)r R = 256 ppr the maximum frequency of the outputs signal of theencoders (standard 100 kHz), thefrequency is directly related to the resolution andthe rotation speed ofthe shaft the maximum frequencywhich can be read by the subsequent circuitry
SIGNALS USE
1 channelA signals (eventually complementedwith A\)are classically used for measuring speed, but without detection of the direction of rotation2 channels, A and B (possiblycomplementedwith A\ and B\) areused for measuring movements, lengths, anglewithout absoluteposition,the detection of the rotation sense is possible as A and B are electrically phase-shifted at 90°3 channelsA, B and 0 signals(complemented with A\, B\ and 0\), are used for the sameapplications, butwith the possibility to control the number ofcounts with the0signalonceper revolution.BEIIDEACODhas threedifferentwaysin which to gate the0channel: in the standard it is gated on A and B,gated on A or un-gated 0 signals are optional
Changes possible withoutfurther notice- Version2.0 10 www.bei-ideacod.com